Power Resilience

How McMinnville Electric System’s Diesel Generators Support TVA During Grid Emergencies

When extreme weather or grid emergencies threaten the Tennessee Valley, McMinnville Electric System (MES) stands ready to provide critical backup power generation. As the first local power company (LPC) in the Valley to install and operate diesel generators in partnership with TVA, MES has played a pioneering role in bolstering system reliability for more than two decades.

With 23 megawatts (MW) of generating capacity, MES’ diesel generators are a proven resource that can be called upon during peak demand periods and emergency situations. As the Valley’s energy landscape continues to evolve, MES is exploring new ways to expand its impact — both through continued collaboration with TVA and by advocating for greater flexibility in how its assets can be used.

A Vision for Energy Security: The History of MES’ Backup Generation

McMinnville Electric System’s investment in backup generation dates back to the early 2000s. At the time, newly hired General Manager Rodney Boyd pulled the plug on a cable TV project after the feasibility study showed the project did not have a favorable rate of return. As that initiative stalled, the operations superintendent recognized an opportunity in power generation instead. Inspired by another utility in the Valley, MES decided to install its own generation system — marking the beginning of its long-standing role in supporting TVA’s grid stability.

“That decision led to the installation of eleven diesel generators, which we still use today,” says Brittany Davis, General Manager of MES. “Later, at the recommendation of a City Alderman, we added a biodiesel generator to our fleet, bringing our total capacity to 23 MW.”

The first power purchase agreement (PPA) with TVA was signed in 2001, setting the foundation for MES’ role as an energy provider during grid emergencies.

Supporting TVA During Critical Grid Events

Unlike other backup generation assets used for daily operations, MES’ generators are strictly contracted for use during TVA-declared grid emergencies. They remain idle unless TVA calls on them during times of extreme weather or peak demand.

“For example, during the severe winter storm in January, we were asked to run between 2 a.m. and 10 a.m. on the 22nd,” Davis shares. “We responded with 20.3 MW of generation, directly supplementing TVA’s supply during a high-demand period.”

This kind of localized generation plays a crucial role in stabilizing the Valley’s grid, reducing the likelihood of forced curtailments and improving reliability across the region.

Looking Ahead: Expanding MES’ Role in Grid Resilience

With its original contract set to expire, MES is now in discussions with TVA to extend its agreement for another 10 years. However, Davis hopes that the new contract will allow for greater flexibility in how MES’ generation assets can be utilized.

“I’m hopeful that TVA will consider allowing us to use our assets outside of emergency response scenarios in future agreements,” Davis explains. “Right now, our generators are only used when TVA calls on them, but they could provide value in other ways if the contract allows.”

Additionally, MES has explored switching to natural gas generators, which would provide cleaner generation options. However, significant space limitations at the substation and the reality that natural gas would cut the system’s generating capacity by half have made this transition less viable.

Lessons for Other LPCs Considering On-Site Generation

As other LPCs explore backup generation options, MES’ experience provides key insights into financial, operational and regulatory considerations.

Identifying your driving goal is a critical first step in any energy project. Are you motivated by a financial incentive, like stabilizing rates for your customers? Perhaps you’re looking to appeal to environmentally conscious consumers by incorporating renewable energy sources. Or maybe your goal is to invest in backup generation or contribute to broader capacity solutions for the grid. Understanding what you want to achieve will guide your decision-making process.

“Before making an investment, you have to determine what you hope to accomplish with your project,” Davis advises. “For us, the ability to generate additional revenue while keeping residential rates stable was a major factor.” Over the years, MES’ diesel generation has helped maintain affordable rates for its customers, proving that local generation can provide both economic and reliability benefits. However, Davis also acknowledges that the regulatory and permitting process is significant. “It’s a major undertaking, but it’s manageable,” she says. “The bigger challenge is aligning with TVA’s flexibility guidelines and understanding how your generation assets will fit within that framework.”

The Future of Local Power Company Involvement in Grid Resilience

Davis believes that LPCs can play a larger role in strengthening the Tennessee Valley’s energy future — but only if TVA allows for greater integration of distributed generation resources. “I think the possibilities are endless, but it ultimately depends on what TVA will allow,” she says. “Decentralizing power generation and modernizing the grid will be key to sustaining the public power model.”

This view aligns with a growing consensus among experts who see decentralizing power generation and modernizing the grid as essential strategies for enhancing both energy reliability and security. Decentralized systems, for instance, can help safeguard against disruptions in centralized infrastructure, whether caused by severe weather, cyberattacks or vandalism.

Currently, TVA’s Flexibility 2.0 Program allows LPCs to contribute up to 5 percent of their system peak through third-party generation. However, as Davis points out, MES’ diesel generators don’t fall within this program’s parameters, highlighting the need for expanded flexibility in how LPCs can contribute to energy solutions.

Beyond Generation: Building a More Resilient Energy Future

While backup generation remains MES’ primary contribution to grid resilience, Davis sees other technological advancements as equally critical for the future.

“Partnership is key,” she emphasizes. “The more LPCs and TVA work together, share resources, and align goals, the more resilient our system will become.”

Davis points to TVA’s new Dispatchable Voltage Regulation (DVR) project as a promising step forward — particularly for LPCs with voltage regulation devices. However, she notes that not all LPCs have access to the same modern technology, making it essential to prioritize system upgrades across the region.

“Some systems still rely on outdated, inefficient equipment,” Davis says. “If we’re going to build a truly flexible, resilient energy future, we need to make sure every LPC has the tools to contribute.”

Leading the Way for Local Generation

McMinnville Electric System’s role in pioneering local power generation proves that LPCs can play a vital part in strengthening the grid. As the first system in the Tennessee Valley to install and operate diesel generators for TVA, MES has demonstrated how localized energy solutions can enhance reliability, reduce demand during critical events, and support a stronger public power model.

With contract negotiations underway and the potential for expanded flexibility in the future, MES remains committed to advancing local generation as a key component of grid resilience.

“As the energy landscape evolves, we have to keep looking ahead and adapting our approach,” Davis says. “By working together and leveraging all available resources, LPCs and TVA can create a more reliable, efficient, and cost-effective energy future for the entire Valley.” 26 TVPPA.